PROJECT SUMMARY/ABSTRACT Business establishments hold potential to shape individual behaviors and experiences relevant to cognitive decline including mobility and management of Alzheimer's disease related dementias (ADRD). Policies impacting local business environments may prevent ADRD onset, extend years of healthy life, and facilitate independent living. The proposed project is leverages data we have assembled on business environments and other dynamic geographic contexts across decades to expand our CVD-focused work into the area of cognitive decline and ADRD. Longitudinal studies of local environments have been strongly recommended as future research to advance our understanding of causal neighborhood effects on health. The local density of businesses with potential relevance to health has changed over time, and such temporal fluctuations vary across regions, cities and neighborhoods. These differences can be used to investigate how residentially stable older adults are affected by their local context. Older adults who relocate to a new home address may respond to their new context by changing health behaviors, offering another window into causation. Attention is needed to cognitive changes that may precipitate relocation, and which local environment features predict aging in place despite new health or functional limitations. In the proposed project, we will link longitudinal data to investigate how neighborhood change and residential relocation shape cognitive decline, ADRD, and related health disparities. We will use the National Establishment Time Series (NETS) database, a census of >58 million US business establishments, including annual point-level geocodes and business characteristics for the years 1990-2014,offering an opportunity to characterize changing business environments nationally at multiple spatial scales. Geographic context data (from NETS and longitudinal population, safety, and transportation data) will be linked to individual data from two cohort studies: Cardiovascular Health Study (CHS) and Reasons for Geographic and Racial Differences in Stroke (REGARDS) Study, both of which have ADRD relevant cognitive measures and assessments. CHS is a well-characterized population-based study of 5,888 older adults (100% age 65+ at baseline, 58% female, 16% African American). A majority of the CHS participants enrolled 1990-1993 from four US sites have been followed prospectively, with longitudinal cognitive assessments and adjudicated dementia status during follow-up. REGARDS is a prospective population-based cohort study, including oversampling of African Americans and Stroke Belt residents. The 30,239 REGARDS participants (49% age 65+ at baseline,55% female,42% African American) were enrolled in 2003-2007, from the 48 contiguous US states, and cognitive assessments were administered throughout follow-up allowing cognitive function and decline to be investigated. For both cohorts, longitudinal addresses have been georeferenced and surrounding areas characterized. This project brings unparalleled geographic resources along with comprehensive cohort data to inform how community design can support healthy aging.